1. Field of the Invention
This invention relates to devices, systems, and methods for reinforcing construction materials and, more particularly, to devices, systems, and methods for reinforcing concrete and/or asphalt cement, in which the devices, systems, and methods include metallic or non-metallic coil wires that can include a plurality of metallic or non-metallic load transfer tabs distributed thereon.
2. Background of the Related Art
Throughout most of the United States, roadways, typically, are made of rigid concrete slabs or a more flexible pavement such as asphalt cement or a combination of the two. When design loads necessitate, concrete pavements are steel-reinforced to provide tensile strength to the concrete, which has an inherently high compressive strength but, relatively, a very low tensile strength. Traditional steel reinforcement, especially for concrete, assures ductile failure of the concrete prior to a catastrophic failure of the steel. Although a “ductile-failure assured” mode of failure is more important when dealing with concrete beams and columns for which catastrophic failure of the steel could result in loss of life and severe damage, the design concept or mode of failure is equally applicable to design of transportation structures like roadways.
Traditionally, tensile reinforcement for concrete structures, e.g., roadway pavements, structural slabs or the like, is provided using one or more levels of steel reinforcing bars (“rebar”). Optionally, when minimal tensile reinforcement is needed, welded-wire fabric (“WWF”) can be used to provide some tensile strength, but, more preferably to provide reinforcement against shrinking or cracking that may result from temperature changes.
The placement of steel reinforcement, whether as WWF or rebar, is a complex procedure made even more so by having to raise the bulky WWF or rebar a vertical distance—typically about three inches or more—above grade elevation, to ensure adequate cover to protect the rebar or WWF from the ill effects of water and oxidation. This often entails using stirrups or some other readily available construction or scrap material to elevate the rebar or WWF. This is far from a perfect solution, however.
Furthermore, notwithstanding over-design and over-reinforcement, rebar and WWF as reinforcement media still do not prevent tension cracking of the concrete or asphalt cement, which, typically, first, occurs in the cover area between the rebar or WWF and grade. Tensile cracking can lead to progressive failure of the concrete system, which manifests as unsightly and annoying ruts, potholes or the like.
Asphalt cement, a specifically engineered blend or mixture of a bituminous bi-product and aggregates, is typically used for flexible pavement design. Flexible pavements are normally cheaper to build and maintain than reinforced concrete slabs. However, by their very flexible nature, they can deteriorate and fail more rapidly than concrete roadways.
A common—if not the most common—failure mode of flexible pavements is by reflective tension cracking. Compressive forces at the roadway surface are transmitted through the flexible pavement and applied to the prepared subsoil, base course material or previous roadway on which the new pavement was constructed. This load can cause the subsoil or base course to compress. When the subsoil or base course compresses, the overlying flexible pavement is placed in tension, causing tensile cracks in the bottom portion of the asphalt cement matrix. With time and repeated loading, the tensile cracks can make their way to the roadway surface, i.e., “daylight”, and, progressive failure of an asphalt cement system results. This, too, manifests as ruts, potholes or the like.
Others have proposed various methods, systems, and devices for reinforcing flexible pavements. For example, plastic materials, e.g., geo-grids and geo-textiles, and woven and non-woven overlay fabrics have been provided between the interface between the new asphalt cement roadway and any previous subsurface, whether a natural soil or a previous pavement. Steel is impractical because asphalt cement structures are generally porous and therefore prone to water infiltration that can oxidize or corrode the steel.
Encasing steel in an epoxy coating to guard against corrosion is a possible solution. However, “modern” construction techniques cannot guarantee the integrity of the epoxy coating during or after installation. Coating rebar also adds additional cost, which escalates the cost of constructing a horizontal roadway that covers hundreds of miles. Reinforcing bars made of a fiberglass composite and/or using nail- or pin-size steel, nylon or fiberglass fibers to reinforce the concrete have also been proposed and used with some success. However, concrete admixtures are prone to clumping and uneven distribution throughout the concrete or asphalt cement substrate.
Therefore, it would be desirable to provide devices, systems, and methods for reinforcing a construction medium, e.g., concrete, asphalt cement, and the like economically, to minimize tensile failure of the medium that occurs when WWF and/or rebar are used.